Our caring government's next security measures, I am unreliably informed, will require us all to have bar-codes tattooed inside our nostrils. This identifying mark must be shown to any civil servant, busybody or nostril voyeur who asks. Refusing access to your nostril will (as designated in the "Who Cares About Terrorism, Let's Annoy The Public Some More" Act of 2007) earn you a free trip to Guantanamo Bay. Have a nice day!
Naturally SF has speculated a lot about such invasions of privacy. A favourite gadget, much more insidious than CCTV, is the time viewer. The techno-details vary between stories, but essentially it's a spy camera that peeps into the past to display scenes from anywhere and anywhen.
In Isaac Asimov's 1956 story "The Dead Past", this "chronoscope" is supposedly a research tool for historians. The big secret, covered up by the government, is that it's useless for ancient history. Its effective range is barely more than a century, and even then the results are blurry. The best images come from just a second ago, or a microsecond. Spying on the past means being able to spy on the present.
Asimov's story ends on a note of shuddering horror, with the chronoscope technology released to the world and all personal privacy about to end. But the heroes of another time-viewer story, T.L. Sherred's "E For Effort" (1947), believe that this total transparency will be a good thing – at least in terms of politics. As one of them says, "with every plan open to inspection as soon as it's made, no nation or group of nations would have a chance in open warfare." The US military agrees, and before you can say Data Protection Act, World War III has been launched to keep the time viewer secret. Not a cheerful story.
Damon Knight managed to be surprisingly optimistic about the annihilation of privacy in "I See You" (1976). His anonymous inventor has obviously read the Sherred tale, and takes great care to secretly manufacture and distribute ten thousand space/time viewers – with instructions – before the US military can interfere. At first there's a fair amount of upheaval, but the outcome is a kind of glass-walled utopia. Knight's future children grow up being able to zoom in on all the naughty things adults used to do behind closed doors, and no one is embarrassed any more. The author called it a "wish-fulfilment fantasy." Being a massively inhibited child of the barbaric 20th century, I get the screaming heeby-jeebies just thinking about it ...
So presumably do the galactic races in Piers Anthony's early novel Macroscope, who have a cunning answer to Earthlings who try to snoop on their affairs with the super-telescope of the title. They broadcast a special "Destroyer" signal on the macroscope waveband, a visual presentation which literally blows the minds of interstellar voyeurs. Rough justice. Princess Diana would have loved one of those, for use on the paparazzi.
In his 1966 story "Light Of Other Days", Bob Shaw came up with a different approach which at first glance doesn't look like a time viewer at all: "slow glass". Light takes a very long time to make its way through this unusual glass. People buy luxury window panes which have stored up ten years of idyllic country views, and instal them in their horrible city apartments.
Of course, slow glass has a way of recording scenes that weren't meant to be preserved. Shaw's story has an unforgettable punchline which I won't spoil here. By the end of the novel he built around his various slow glass stories (Other Days, Other Eyes), the government is using crop-sprayers to dust the whole country with recording glass particles. Now they can find out everything we've done in the recent or not-so-recent past. It's Tony Blair's dream of total surveillance, come true at last.
Stephen Baxter and Arthur C Clarke (mostly Baxter, I suspect) updated the theme with some doubletalk about wormholes, and explored deep time in The Light Of Other Days – whose title seems awfully reminiscent of some Bob Shaw story. Sheer coincidence!
Meanwhile, for those who've had enough stories about viewing the dead past, the distinguished fantasy author Lord Dunsany produced an SF novel about a gadget that works the other way. Written in 1955, it somehow wasn't published until 2003, and the title says it all: The Pleasures Of A Futuroscope.
David Langford's 2006 Christmas list includes a futuroscope tuned to the London Stock Exchange.
PS: When this appeared, Stephen Baxter smugly pointed out that he too had covered this subject in a Foundation essay called "The Technology of Omniscience" (2000), reprinted in his collection Omegatropic.